This invention pertains to computer and other information handling systems wherein "option cards" or "adapter cards" can be plugged into and removed from the system without turning the power to the system OFF, and, more particularly, to an improved mechanical card insulator and guide that prevents accidental shorting during the insertion or removal of an adapter card.
Computer systems usually have a main printed circuit board commonly called the "motherboard." The motherboard is usually equipped with a plurality of card edge connectors for receiving adapter cards. These adapter cards are designed to provide optional and additional functions that the base system on the motherboard does not provide. In many computer systems, the insertion or the removal of an adapter card requires that the power to the system be turned OFF. In more advanced systems, adapter cards can be plugged into and unplugged from the system while the power to the system is ON. Plugging an adapter card into or removing it from a system while the power is ON is generally referred to as "hot-plugging."
Since most adapter cards have a metal bracket at one edge of the card, and because the power to the motherboard is not turned OFF in a "hot-plug" system during insertion or removal of an adapter card, the accidental contact of the metal bracket to the motherboard can result in an electrical short. In addition, during insertion or removal of an adapter card, the accidental contact of an adapter card to an adjacent adapter card already installed in the system can also result in an electrical short. Furthermore, accidental shorting can also result from small metallic items, such as nuts, bolts, screwdrivers, pens and pencils, being accidentally dropped on a "live" motherboard when the system housing has been opened to insert or remove an adapter card.
To overcome these problems, at least two solutions have been used in the past. In the first solution, the motherboard is covered with a "motherboard insulator," which is comprised of a large sheet of semi-rigid or rigid plastic. The adapter card connectors on the motherboard are accessible to the edge connector of an adapter card through a plurality of slots in the motherboard insulator. Positioned between each of these slots in the motherboard insulator is a mechanical connector. A substantially rectangular card insulator, which is comprised of a thin sheet of semi-rigid or rigid plastic, is positioned between two adjacent adapter cards and attached to the mechanical connector on the motherboard insulator such that the card insulator is supported in a position substantially perpendicular to the motherboard and the motherboard insulator.
In the second solution, the motherboard insulator is comprised of a pliable sheet of plastic that covers the motherboard. The card insulators are inserted between the adapter cards, but are not attached to the motherboard insulator as in the first solution. Instead, each of the two opposite vertical edges of a card insulator are held by plastics guides, which are attached to the frame of the computer system.
There are a number of problems and disadvantages to each of these prior art solutions. One disadvantage to both solutions is that the entire motherboard is covered with a plastic sheet, thereby effecting cooling by reducing the air flow over the motherboard. It would also be desirable if the motherboard insulator could be eliminated entirely, thereby reducing the cost of protecting the system from inadvertent electrical shorts. In the first solution, the insulator connectors usually tightly bind the card insulators, thereby making it difficult to remove an individual card insulator. Furthermore, while the entire assembly of motherboard insulator and card insulators can be removed, this requires that all adapter cards be removed first. In this respect, the second solution is better, because it permits the easy insertion and removal of individual card insulators.
Accordingly, the invention described below overcomes many of the disadvantages of the prior art solutions by eliminating the motherboard insulator, while still providing protection against electrical shorts during insertion and removal of adapter cards, as well as providing protection against shorts caused by the inadvertent dropping of small metallic parts over the motherboard.